Lipid Formulations for Patients Requiring Parenteral Nutrition: A Review of Clinical Effectiveness, Cost-Effectiveness, and Guidelines – An Update [Internet]

Excerpt

Parenteral nutrition (PN) is provided through intravenous administration to patients who are unable to meet their nutritional needs either through oral intake or enteral nutrition (EN) due to pathological or surgical conditions.^– Decades of research have resulted in the development of relatively safe PN formulations containing amino acids, glucose, lipids (as emulsions), electrolytes, vitamins and trace elements. PN may be used for short or long periods of time depending on the morbidity and its severity. However, prolonged use of PN may be associated with increased risk of long-term adverse events including hypertriglyceridemia, infections, metabolic bone disease, and PN-associated liver disease (PNALD).^,

The source of oil present in lipid emulsions is believed to play an important role in the development of long-term complications. Soybean oil (SO) is not only an excellent source of non-protein energy, but also rich in essential fatty acids such as linoleic acid (18:2 n-6) and alpha-linolenic acid (18:3 n-3) and non-essential oleic acid (18:1 n-9). The letters “n” and “ω” for omega are used interchangeably. These fatty acids are precursors of longer chain fatty acids, arachidonic acid (AA; 20:4 n-6), eicosapentaenoic acid (EPA; 20:5 n-3), and eicosatrienoic acid (Mead acid, 20:3 n-9), respectively. AA and Mead acid have more proinflammatory properties than EPA. Prolonged use of SO emulsions in PN has been associated with hypertriglyceridemia, proinflammatory profile, and PNALD.^, As a result, different lipid formulations have been developed.

For instance, olive oil (OO) has been added to reduce the amount of SO in lipid emulsions for PN. OO is the main source of lipid in the Mediterranean diet, consisting of monounsaturated fatty acids such as oleic acid (18:1 n-9), phenolic compounds, and squalene. Diets enriched with OO have been linked to health benefits such as prevention of cancer, heart disease, and aging through its antioxidant properties. Compared with pure SO emulsion in PN, a mixture of 80% OO/20% SO has been shown to have some clinical benefits, despite the concern about the increase in Mead acid levels in OO enriched lipid emulsions.

Another lipid has been used to reduce the level SO component in lipid emulsions for PN was medium chain triglycerides (MCT), containing fatty acids of 6 to 12 carbon atoms. Unlike long chain triglycerides (LCT) with fatty acid chains ranging from 14 to 21 carbon atoms, MCT are more water soluble and readily oxidized in the mitochondria for the production of energy. A mixture of 50% MCT/50% LCT has been developed and considered to be safe and tolerable in patients requiring PN. However, the beneficial effects of MCT/LCT compared with other lipid emulsions for PN remains unclear.

Fish oil (FO) has lately been considered as an ideal choice of lipid to partially or completely replace SO. FO has a high content of n-3 polyunsaturated fatty acids (20% to 40%), particularly EPA and docosahexaenoic acid (DHA; 22:6 n-3), which have been shown to reduce inflammation by competing with AA for eicosanoid synthesis, producing the 3-series of prostaglandins and thromboxanes and the 5-series of leukotrienes. Mixed-oil containing FO for use in PN such as SO/MCT/OO/FO (30%/30%/25%/15%) or MCT/SO/FO (50%/40%/10%) has been recently developed and is available for PN use. From small-scale clinical trials, fish oil enriched PN appears to have some clinical benefits compared with non-fish oil enriched PN.^,

In a recent CADTH report, published in 2017, entitled “Lipid Formulations for Patients Requiring Parenteral Nutrition: A Review of Clinical and Cost-Effectiveness and Guidelines”, low quality evidence found no difference in comparative clinical effectiveness among lipid emulsions examined in preterm infants. There was some evidence that fish oil enriched PN had some clinical benefits in non-surgical and surgical adult patients in intensive care unit (ICU). Economic evaluations from low-quality studies showed that FO emulsion was more cost-effective than SO-based emulsions. None of the identified guidelines could make strong recommendations regarding the type of lipid emulsions for PN due to insufficient evidence.

The aim of this report is to update the clinical effectiveness, cost-effectiveness, and evidence-based guidelines on the use of lipid formulations for patients requiring PN.